The present invention relates to prosthetic heart valves. More particularly, the invention relates to an increased valve lumen of a prosthetic heart valve to improve hemodynamic performance.
Prosthetic heart valves are used as a replacement for natural heart valves of patients. A standard implantable mechanical heart valve typically includes an annular valve housing or body (often called an xe2x80x9corificexe2x80x9d) to provide a lumen or passageway therethrough for blood flow. One or more occluders mounted to the valve are movable between an open position, allowing blood flow, and a closed position which blocks blood flow. In many mechanical valves, the occluders are essentially plate-like members called xe2x80x9cleaflets.xe2x80x9d Typical configurations include one, two or three leaflets in the valve body.
There has been an ongoing effort to improve the performance of prosthetic heart valves. One important factor in heart valve performance is the flow characteristics through the valve when the leaflets are in a fully open position. Compared with native valves, mechanical heart valves have flow characteristics with higher peak velocities and greater variation in velocity across the valve, leading to higher shear stresses and a more turbulent flow structure. As a result, prosthetic heart valves have higher energy loss and correspondingly higher pressure differentials across the valve than the native valve. The forward flow characteristics of the valve can be altered by increasing the valve lumen area allowing full alignment of the leaflets with the direction of flow, and improving the shape of the lumen valve among other techniques.
Another problem which may be associated with mechanical heart valves relates to formation of thrombus and thromboembolism. Thrombus and thromboembolism are known complications of mechanical heart valves and can result in serious disability or death. To help prevent these complications, a common treatment involves life-long anticoagulant therapy. However, anticoagulant therapy itself leads to an increased risk of anticoagulant-related hemorrhage.
Factors which influence the risk of thrombus and thromboembolism formation for mechanical heart valve patients include the nonphysiological surfaces and blood flow introduced by mechanical valves. Further, typical mechanical heart valves subject the blood to high shear stress, largely because such valves tend to produce high velocity gradients and turbulent flow structures. High shear stresses are known to activate blood platelets and damage red blood cells. The activated platelets have the potential to be deposited on the valve or downstream from the valve and to aggregate into thrombi. Therefore, valves with mean forward flow velocities and peak shear stresses which are lower than prior art valves would be beneficial to patients.
A prosthetic heart valve for replacing a native valve in a heart is provided and includes a generally circular heart valve body having an inner wall defining an orifice configured to allow blood flow therethrough. At least one occluder in the orifice is configured to rotate about opposed occluder ends between an open position and a closed position. The occluder is configured to substantially block blood flow through the orifice in the closed position. In one aspect, minor radius arcs are formed in the inner diameter of the heart valve body to receive the minor radius arcs of the occluder. The curved surface with minor radius arcs extends the full length of the orifice to seal the occluders in the closed position and allow the occluders to rotate to a fully open position without interference.